hopkins



Nov. 22, 1955 L. o. HOPKINS 2,724,135

BASCULE BRIDGE Filed Oct. 6, 1950 2 Sheets-Sheet 1 FIG. 2.

IN V EN TOR.

L. O. HOPKINIS BY ATTORNEY Nov. 22, 1955 L. o. HOPKINS 2,724,135

BASCULE BRIDGE Filed Oct. 6, 1950 2 Sheets-Sheet 2 FIG. 3

IN VEN TOR.

L. O. HOPKINS United States Pa BASCULE BRIDGE Leonard 0. Hopkins, Nashville, Tenn. Application October 6,1950, Serial No. 188,811 4 Claims. (or. 14-36) This invention relates to a bridge construction and more particularly to a bridge having a lift span of the bascule type and an improved operating mechanism therefor.

. In my Patent 2,066,110, dated December 29, 1936, there is disclosed a construction and operating mechanism for the lift span of bridges of the bascule type which compensates for small inaccuracies in the erection of the bridgeand yet maintains the drive and gear assembly in proper engagement with the segmental rack on the lift span.

In this type of construction, particularly in large structures, it is sometimes desirable to provide two racks and a drive unit which equalizes the pressure exerted by the pinion gears on the racks.

One object of the present invention is to provide a construction and operating mechanism for bascule type bridges wherein the drive mechanism is maintained in proper engagement with spaced segmental racks on the lift span and assures an equal pressure on both racks.

Further objects and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, wherein:

Fig. l is a side elevational view of a portion of a bridge illustrating one application of the present invention;

Fig. 2, a partial longitudinal section through the bridge construction shown in Fig. 1 on an enlarged scale and illustrating one preferred embodiment of the operating mechanism of the present invention; and

Fig. 3, a transverse sectional view taken on the line 3-3 of Fig. 2.

Referring now to the drawings in detail, a bascule type bridge is shown in Fig. 1 having a fixed portion and movable portion or a bridge leaf or lift span 11 which is shown in phantom lines in the raised position.

The bridge leaf 11 is pivotally mounted on bridge supporting structure such as a pier 12 and is raised and lowered by an operating mechanism which is generally indicated by the numeral 13 and is pivotally mounted in bearings 14 resting on pier 12.

With particular reference to Figs. 2 and 3, wherein the operating mechanism is shown on an enlarged scale with the outer portion of the bridge leaf broken away, the bridge leaf 11 is pivotally mounted by means of trunnions 15 which are journaled in bearings 16 mounted on the pier 12. Trunnions 15 are rigidly connected to girders 17 and 18 which are secured to the platform 19 of the bridge leaf. A pair of segmental racks 20 are secured to a pair of girders 21 which are also secured to the platform 19, and the center of curvature of the racks 20 is preferably in alignment with the axis of the trunnions 15.

The operating mechanism 13, as shown, consists of a framework 22 on which is mounted a motor 23 driving a reduction gear box 24 through a coupling 25. Gear box 24 is also connected through a clutch 26 to a shaft 27 having a spur gear 28 engaging a smaller spur gear 29 on a shaft 30. The outer ends of shafts 27 and 30 may be provided with a suitable connection or crank 30 for 2,724,135 Patented Nov. 22, 1955 operation by hand or by a portable power unit in case of failure of the motor 23.

A shaft 31 is driven by the gear box 24 and has mounted thereon a pinion 32 engaging a ring gear 33 on the housing of a differential unit 34. A pair of coaxial shafts 35 are driven by the differential unit 34 and are provided adjacent their outer ends with pinions 36 engaging the racks 20. A pair of links 37 are pivotally connected at their outer ends to stub shafts 38 extending outwardly from the pinions 3'6 and at their inner ends are pivotally mounted on stub shafts 39 extending outwardly from the racks 20 and preferably located on the center of curvature of the racks 20 and coincident with the axis of the trunnions 15.

In the operation of the mechanism the differential unit 34 is driven through gear box 24 by the motor 23, or byhand operation or a portable unit through shaft 27 and clutch 26. The structure and operation of the differential unit is conventional and the details of construction are therefore not shown in the present application. The shafts 35 may at times rotate at slightly different speeds in order to equalize the pressure exerted by the pinions 36 on the corresponding racks 20 for raising and lowering the bridge leaf 11.

If, for any reason, the machinery support, racks and trunnions are not accurately positioned or are misaligned relative to each other during erection, or if the relative positions are varied subsequently either by shifting of the parts or by movement due to changes in the weather, the load or the like, the present construction will compensate for such inaccuracies and variations and still maintain the proper engagement and assure an equal pressure on both racks. Such compensation is obtained by the transmission and distribution of the force required to operate the bridge leaf or movable portion of the bridge to the bridge operating mechanism, namely, the sets of racks and pinions or the like, by the use of compensating mechanism as for example, by the use of a differential drive between the cooperating sets of racks and pinions, thereby transmitting and distributing the load to the multiple sets so that such load will be jointly carried and avoiding the load being carried by a single set.

It will be obvious to those skilled in the art that various changes may be made in the invention without departing from the spirit and scope thereof and therefore this invention is not limited by that which is shown in the drawings or by that which is described in the specification but only as indicated in the appended claims.

What is claimed is:

1. In a bascule bridge the combination of supporting structure, a bridge leaf mounted on said supporting structure, operating mechanism for producing movement of said bridge leaf comprising sets of cooperating racks and pinions disposed on said supporting structure and bridge leaf in such transversely spaced relation so that the load opposing movement of said bridge leaf will be distributed between said sets, a source of power, a driving connection between said source of power and said sets of cooperating pinions and racks, means for compensating for misalignment of said cooperating pinions and racks including a differential interposed between said spaced sets of pinions and racks in said driving connection in a manner to transmit and distribute the driving force to said spaced pinions and racks upon said misalignment.

2. Operating mechanism for the bridge leaf of a bascule bridge comprising sets of cooperating racks and pinions for disposition on said supporting structure and bridge leaf in such transversely spaced relation so that the load opposing movement of said bridge leaf will be distributed between said sets, a source of power, a driving connection between said source of power and said sets of cooperating pinions and racks, means for compensating for misaligndifferential interposed between" said spaced sets of pinio'ns and racks in said driving connection in a manner to transm-it and distribute the driving force to said spaced pinions and racks upon said misalignment.

3. In a bascule bridge a movable bridgeleaf, supporting structure mounting said bridge leaf, operating mechanism for said bridge leaf comprising sets of cooperating members disposed in transversely spaced relation on said bridge leaf and the supporting structure therefor so that the force required to operate said bridge leaf is distributed between said; sets of operating members, a source of power, a driving connection between said source of power and said sets of operating members, and compensating means interposed between said sets of operating members and said source of power of a character to transmit and distribute thedriving force upon the sets of operating members proportionately to said sets of operating members so that such load will be jointly carried.

supporting structure therefor so that the force required to operate said bridge leaf is distributed between said sets of References Cited in the file of this patent UNITED STATES PATENTS 956,143 McGill Apr. 26, 1910 1,320,541 Funk Nov. 4, 1919 1,424,118 Rarner July 25, 1922 2,041,665 Paine May 19, 1936 2,066,110 Hopkins Dec. 29, 1936 2,336,911 Zimmermann Dec. 14, 1943 2,337,994

Hanover, Jr Dec. 28, 1943 

